A new study urges caution among pregnant women who take over-the-counter drugs — products containing acetaminophen may increase your child’s risk of developing attention-deficit hyperactivity disorder (ADHD) later in life.
The long-term study, which tracked more than 112,000 Norwegian children for years, found that long-term use of acetaminophen, also known as paracetamol, led to a doubling of the risk of an ADHD diagnosis. The researchers stress that the link is found only among women who took a product containing acetaminophen for 29 days in succession or more.
“We found that it was safe to use paracetamol for a few days, for example, for a fever,” said Eivind Ystrom, a researcher at the Norwegian Institute of Public Health. “It may even be beneficial because it reduces the period the fetus is exposed to high temperature.”
Otherwise, women seeking relief from long-term pain or other reasons should be careful when navigating their options at the drugstore. Acetaminophen can be found in hundreds of products, including many over-the-counter options. Perhaps the best known is Tylenol.
“Pregnant women who need pain relief over extended periods of their pregnancy should consult their doctor. For example, if they have migraines and consider using paracetamol for longer periods,” says Ystrom.
While the researchers add that the occurrence of ADHD may have other causes, they were able to rule out a lot of other factors during their analysis.
“Short-term maternal use of acetaminophen during pregnancy was negatively associated with ADHD in offspring. Long-term maternal use of acetaminophen during pregnancy was substantially associated with ADHD even after adjusting for indications of use, familial risk of ADHD, and other potential confounders,” report the researchers in the journal Pediatrics.
About 11% of children between the ages of 4 to 17 have been diagnosed with ADHD, according to national statistics, and many children wind up on medication or other therapy.
More Evidence Adds Up
The latest research from Norway adds to a growing body of literature about the unintended consequences of acetaminophen use.
“In 2013, researchers conducting a sibling comparison in a large, population-based Norwegian birth cohort study suggested that prenatal acetaminophen use for 28 or more days was associated with poorer motor and communicational development and externalizing problems (i.e., inattentiveness and aggression) in offspring,” note the researchers.
Other new research added to the acetaminophen-linked findings.
“The following year, researchers conducting a large Danish birth cohort study found an association between prenatal acetaminophen use and both a clinical [ADHD] diagnosis and ADHD symptoms in offspring; later, researchers in other studies related prenatal acetaminophen use to rating scales of disinhibited behavior.”
However, these recent studies had a significant shortcoming. They didn’t factor out a person’s genetic background.
“It is therefore possible that acetaminophen use during pregnancy could be influenced by familial factors (including genetic influences) that may also influence the risk of offspring ADHD,” report the researchers. Understanding this, they add: “We were able to adjust for indications of acetaminophen use and parental symptoms of ADHD.”
In other words, they factored a parent’s own ADHD into the equation and still found the big increase in risk.
Richard Scott is a health care reporter focusing on health policy and public health. Richard keeps tabs on national health trends from his Philadelphia location and is an active member of the Association of Health Care Journalists.